Disk drives are commonly used to store large amounts of data in a readily available form. Typically, the primary components of a disk drive are a head disk assembly and a printed circuit board assembly (PCBA) which, when fixed to one another, form a functional unit that is then connected to a computer. The head disk assembly includes a head, and at least one data storage disk mounted on a spindle motor for rotating the storage disk near the head so that read/write operations may be performed on the disk.
A widely used measure of performance of a disk drive is the number of I/O operations performed by the disk drive. As such, it is essential that factors that adversely interfere with such operations be removed or reduced to within acceptable limits. One such adverse factor is low level acceleration, such as linear or rotational vibration. Vibration can be induced due to a number of factors, such as when other disk drives in the same chassis spin or perform seek operations, or external forces on the rack or chassis containing the drive. Another adverse factor is high level acceleration, such as shock forces exerted on the disk drive, such as by an accidental dropping or shaking of the disk drive. When the presence of such adverse factors exceeds acceptable limits of a drive's tolerance, the head may be shaken off-track during the read/write operations, causing delays in the scheduled operations of the drive, or even destruction of existing data on adjacent tracks.
To reduce the effects of the low and high level acceleration, sensors are mounted on the disk drive, such as on the PCBA. Since the required gain and conditioning corresponding to the detection of low level acceleration is different than that of high level acceleration, dedicated sensors are commonly used for each function. The use of multiple sensors, however, increases the overall complexity and cost associated with the manufacturing of the disk drives in today's competitive market.
Accordingly, what is needed is a reduction of the cost associated with using sensors for the detection of vibration and shock forces in disk drives.